This invention relates to a machine which reduces waste material into smaller pieces, and in particular to such a machine which has replaceable teeth on its blade assemblies.
Waste reduction machines are used to break waste material into smaller pieces to make it easier to handle when it is being disposed of. These machines have rotating blade assemblies which engage the material and break it into smaller pieces. The blade assemblies experience considerable wear and breakage so they need to be replaced from time to time. Some of these machines have blade assemblies with replaceable teeth, which allows the teeth to be replaced when they wear or break without having to replace the entire blade assembly. One such machine is shown in Wada, U.S. Pat. No. 5,680,999.
The difficulty with replaceable teeth is that tremendous forces are exerted on the teeth and replaceable teeth are less durable than integral teeth. Replaceable teeth often break at the point of attachment. In addition, replaceable teeth are generally attached to the blade assembly hub with screws, and as the teeth wear the screw heads wear with them and it becomes extremely difficult to remove the screws. As a result it generally is more expensive and time-consuming to replace the teeth of replaceable teeth blade assemblies than it is to replace integral teeth blade assemblies.
The subject invention overcomes the shortcomings and limitations of the prior art replaceable teeth blade assemblies by providing a blade assembly having a hub that is attached to a rotating shaft. Located around the periphery of the hub are a plurality of attachment devices, each of which receives a tooth and attaches the tooth to the hub. In a first preferred embodiment of the invention each attachment device includes a threaded element having an elongate axis which is generally perpendicular to a radial line on the hub which intersects the threaded element. This threaded element secures the tooth to the attachment device.
In another preferred embodiment of the invention each attachment device includes an elongate locking element and each tooth includes an elongate slot which slidably interfits onto the locking element. The locking element and slot are configured to prevent the tooth from moving radially outwardly from the periphery of the hub once the tooth is slid fully onto the locking element. The base of the locking element and the mating portion of the slot are tapered so as to become tightly interconnected when the tooth is fully installed on the attachment device. The threaded element of the first embodiment may be used with this embodiment to pull the tooth fully onto the attachment device against the resistance of the taper and to push it back off again when it needs to be replaced.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.